Topic outline

  • GPS Reference Systems

    Credits: 1 PDH

    PDH Course Description:

    This course summarizes reference systems and datums to which GPS positions can be transformed. In order to understand GPS and its positional information, it is important to understand the reference system on which it is based, and how that reference system relates to the user's local system. The GPS satellites are referenced to the World Geodetic System of 1984 (WGS84) ellipsoid. For surveying purposes, this earth-centered WGS84 coordinate system must be converted (i.e. transformed) to a user-defined ellipsoid and datum, such as the North American Datum of 1983 (NAD83) or the North American Vertical Datum of 1988 (NAVD88).

    Differential positioning partially provides this transformation by locating one of the receivers at a known point on the user's reference datum or frame. However, for more precise applications, the reference datum cannot be considered as absolutely rigid in time.

    Topics:

    • Geodetic Coordinate Systems
    • WGS84 Reference Ellipsoid
    • Horizontal Datums and Reference Frames
    • Transforming between Horizontal Survey Datums
    • Orthometric Elevations, Ellipsoidal Heights
    • Orthometric Height and WGS84 Ellipsoidal Elevation Relationship
    • Geoid Undulations and Geoid Models
    • Using GPS to Densify Orthometric Elevations
    • GPS Vertical Site Calibration
    • GPS Time References

    To take this course:

    1.) Enroll in Course: Click below to enroll:
    (must be logged into your user account)


    2.) Study: Once enrolled, click below to begin the course:

    Download the Study Guide

    3.) Test: Once you've thoroughly read the course materials, please click below to take the final examination.

    Take the final exam

    4.) Certificate: A passing grade of 70% or higher on the exam, is required to receive the certificate of completion for this PDH course.
         NOTE: After the exam is completed, you will need to return to this page, in order to print (download) the certificate of completion.

    Print the Certificate of Completion

    Intended Audience: This course is intended for surveying and engineering professionals whose job description might involve the use of GPS, and GPS referencing systems.
    Publication Source: USACE (Corp of Engineers)

    Donald Parnell, PE

    • Topic 1